A variety of materials have been used to control algae in different environments, such as but not exclusive to: chlorine/bromine based compounds, biguanides, copper salts, silver-based compounds, triazines, quaternary ammonium compounds and polymeric compounds. Each of them has deficiencies related to pH and/or temperature sensitivity, chemical stability and/or compatibility, limited effectiveness, and environmental and/or human toxicity.
For example, chlorine is the sanitizer/disinfectant/oxidizer most widely used by pool owners. It is very effective at killing bacteria, algae and other living organisms. Chlorine is typically added to a swimming pool in tablet or liquid form or is provided by a chlorine generator, which is a device containing electrical cells that generate chlorine from a bank of salt added to the pool water.
However, chlorine has many disadvantages that lessen its desirability for use as an exclusive disinfectant in swimming pools and other recreational water systems. For example, chlorine can combine with ammonia to form chloramines, which are ineffective at sanitizing, disinfecting, or oxidizing. Ammonia is commonly present in pool water from either environmental factors, a build up of fertilizers that are carried by wind and dropped into pools, from swimmer wastes (perspiration, urine, saliva and body oils), or even from some suntan lotions. As a consequence, pool managers often over-chlorinate a pool (>3 ppm) to compensate for the transformation of chlorine into chloramines. Over-chlorination can lead to excessive absorption of chlorine and chloramines through the skin or to inhalation of air or water vapor containing chlorine and chloramines. Athletes who train for many hours in a swimming pool, particularly in an indoor environment, may be particularly susceptible to over-exposure to chlorine and chloramines and may exhibit symptoms of hypersensitivity and asthma-like respiratory conditions.
Moreover, chlorine is unsuitable for aquaculture environments that may contain desirable plants and animals that may be harmed by chlorine or its byproducts. Examples of such environments include aquariums, fish hatcheries, shrimp ponds, crawfish farms, and the like.
Lysozyme is known as a powerful antibacterial protein distributed in various biological fluids and tissues including avian egg, plant, bacteria, and animal secretions. It is also present in human tears, saliva, milk, respiratory and cervical secretions, and it is secreted by polymorphonuclear leukocytes. Lysozyme has been used for its antibacterial properties both in the pharmaceutical and food industries and been regarded as very safe for human use. In fact, lysozyme is one of the antimicrobial factors present in human milk.
U.S. Pat. No. 5,069,717 to Sherba et al. describes microbicidal composition for controlling algae containing synergistic mixture of a diphenylether and lysozyme.
Accordingly, it is desirable to have a method of preventing, killing, and/or inhibiting the growth of microorganisms that is inexpensive and uses an ingredient that is effective at a low concentration and that is easily available.
It is also desirable to have a method of preventing, killing, and/or inhibiting the growth of microorganisms that does not use chlorine or other environmentally undesirable ingredients.